1. Technical Field
The present disclosure relates to a wide viewing angle holographic image display method and apparatus and, more particularly, to a large screen, wide viewing angle holographic image display method and apparatus that provide a wide viewing angle while maintaining the size of pixels that can be fabricated using current technology already commercialized.
2. Description of the Related Art
As “holo” of the term “hologram” implies “complete” and “gram” implies a “message” or “information,” a hologram is a medium that records fringe patterns that reproduce a three-dimensional (3D) image using 3D photographs that appear to be an actual object. Most digital holographic image display apparatuses that have been currently researched use a spatial light modulator (SLM), and their viewing angle varies depending on the size of pixels. That is, a viewing angle increases in inverse proportion to the size of the pixels of a spatial light modulator. A reduction in the size of pixels is limited because of a limited spatial light modulator manufacturing process, thus resulting in a limitation being imposed on viewing angles that can be provided by current digital holographic display apparatuses.
The principle of a holographic image display will be described below.
FIGS. 1 and 2 are diagrams illustrating the principle of a holographic image display.
Referring to FIGS. 1 and 2, for example, in order to provide a viewing angle of about 5 degrees, a spatial light modulator that provides a pixel interval of about 3.5 um is required. Meanwhile, in order to provide a viewing angle in the range of 40 to 60 degrees, which does not cause inconvenience while viewing an image, a spatial light modulator having the size of pixels equal to or smaller than 1 um is required. However, it is impossible to fabricate a spatial light modulator having such a micro-size using current technology.
Japanese Unexamined Patent Publication No. 2004-287440 discloses a configuration for increasing a viewing angle by adjusting the size of the pixels of a light modulator. However, the decreasing of the size of pixels to such a size cannot be accomplished by current technology.
Furthermore, as a method of increasing the viewing angle of a digital holographic display apparatus while overcoming the limitations of a spatial light modulator, a method of finding the location of the eye and generating a virtual window using eye tracking so that a normal image is formed when viewed from the location of the eye is being proposed and researched.
However, this technology is problematic in that it is difficult to find the accurate location of the eye and also it is difficult for multiple people to view a holographic image at the same time using this technology.
Furthermore, in order to enable multiple people to view a holographic image, research is being conducted into a method of increasing the frame rate of a narrow viewing angle holographic display apparatus and generating virtual windows at different locations using a temporal multiplexing method.
However, this technology is limited in an increase in the frame rate of a holographic display apparatus, and thus it is still difficult to increase a viewing angle.